The subject matter disclosed herein relates generally to medical diagnostic imaging systems, and more particularly to bone densitometers.
Dual-energy imaging systems include an x-ray source that emits a collimated beam of dual-energy x-rays to image a patient. An x-ray detector is positioned with respect to the x-ray source to receive the x-rays passing through the patient. The x-ray detector produces electrical signals in response to the received x-rays. The electrical signals are converted to digital signals that are utilized by the imaging system to generate images of the patient.
Measurements of the x-ray absorption by an object at two different x-ray energies can reveal information about the composition of that object as decomposed into two selected basis materials. In the medical area, the selected basis materials are frequently bone and soft tissue. The ability to distinguish bone from surrounding soft tissue allows x-ray images to yield quantitative information about in vivo bone density for the diagnosis of osteoporosis and other bone disease.
At least some known dual-energy imaging systems include detector elements that are fabricated using a Cadmium Telluride (CdTe) semiconductor having conventional ohmic anode and cathode contacts. Under the influence of an applied biasing voltage, the semiconductor generates a current proportional to the energy of each x-ray absorbed by the semiconductor. The slight increases in the semiconductor current due to x-rays are translated into digital signals that are used to generate an image. However, the conventional ohmic contacts may generate substantial leakage current that causes noise and thus reduces the overall quality of the signal used to generate the images.